https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120718
--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Richard Sandiford <rsand...@gcc.gnu.org>: https://gcc.gnu.org/g:8e3239e3e92f3cd57bf3a19f10daa66c4cb45cc1 commit r16-3067-g8e3239e3e92f3cd57bf3a19f10daa66c4cb45cc1 Author: Richard Sandiford <richard.sandif...@arm.com> Date: Thu Aug 7 14:19:03 2025 +0100 Remove MODE_COMPOSITE_P test from simplify_gen_subreg [PR120718] simplify_gen_subreg rejected subregs of literal constants if MODE_COMPOSITE_P. This was added by the fix for PR96648 in g:c0f772894b6b3cd8ed5c5dd09d0c7917f51cf70f. Jakub said: As for the simplify_gen_subreg change, I think it would be desirable to just avoid creating SUBREGs of constants on all targets and for all constants, if simplify_immed_subreg simplified, fine, otherwise punt, but as we are late in GCC11 development, the patch instead guards this behavior on MODE_COMPOSITE_P (outermode) - i.e. only conversions to powerpc{,64,64le} double double long double - and only for the cases where simplify_immed_subreg was called. I'm not sure about relaxing the codes further, since subregs might be wanted for CONST, SYMBOL_REF and LABEL_REF. But removing the MODE_COMPOSITE_P is needed to fix PR120718, where we get an ICE from generating a subreg of a V2SI const_vector. gcc/ PR rtl-optimization/120718 * simplify-rtx.cc (simplify_context::simplify_gen_subreg): Remove MODE_COMPOSITE_P condition. gcc/testsuite/ PR rtl-optimization/120718 * gcc.target/aarch64/sve/acle/general/pr120718.c: New test.
